MaadiMan's play-by-play MG47 build thread

I've been bitten with the belt-fed bug. I've decided to try my hand at building a semi-auto AK-based (loosely) beltfed rifle. My starting point was this:
It's a Romy G kit with an RPD barrel that's been turned down to accept milled Type3 barrel bits. It bores me.
So I got this:
It's an RPD topcover, feedtray, and 100 round belt.

My plan is to join the two in an unholy union, otherwise known as an MG47.
The first step I did was to tackle building a reciever. I built it out of .050" thick 4130 sheet. Here I'm bending it on my super-cheap $35 Harbor Freight brake:
Then I welded up the seam. The seam is on the top surface, so most of it will be cut away and covered by the topcover. I left the piece intentionally long so that I can rivet the trunnion back about 1/3 the length from the front, and have a built in handguard. Kind of a 1 piece receiver/handguard/barrel-shroud like an MG43. Only shorter.

And here it is mocked up with my belt full of empty brass and the topcover/feedtray to give y'all an idea of where I plan on mounting it on the receiver.

I got a little bit done today in between taking the younguns to soccer and starting a batch of biodiesel. I used my flapper wheel to smooth out the weld on the receiver's seam:

Since my mill is packed up and not accessable right now, I used the angle-grinder to cut down the top (bottom) of the rear sight block, so it would fit inside the new receiver. I haven't yet figured out what I'm going to do for the gas-tube, but I figured it would be good to retain the option to still use the gas-tube retainer on the rear sight block:

Then I took a better picture of where I'm at with the trunnion trimming. I still have to cut the ears down a bit more to get the bullet guide to fit up tight into the feed-tray: